struts DAO layer and DTO objects

Hi For my STRUTS PROJECT....I have to connect to a database using DAOs. I used two layerse called DAO (data access objects) and "service" layer where business logic is reside.i used DTO (datatarnsfer objects) for transfer data from frountend to backend.

later i add another layer between frount and service layer called delegate layer to redue coupling.

Actions-->delegate--> service-->DAO

my problom is what kind of methods i have to use in these layerse. do i have to use more specific methods at delegate layer, and fewer and 'more general' ones at the DAO or othr way round?